Green building involves architecture that consists completely of organic materials.

Green buildings are also known as green constructions or sustainable buildings. Theses are structures that use environmentally responsible  and resoure-efficient processes through the building cycle. This includes the design, operation, construction, maintenance, renovation, and even demolition of the structure. It is design to create a balance between homebuilding and a sustainable environment. Though the materials are sustainable, the building ideally provides the same utility, durability, and comfort a regular non-sustainable structure has. 

The right answer is c.sandstone.